Induction rotors having shorted end turn conductors are manufactured in a number of different ways. Aluminum conductor rotors are typically manufactured by a die casting process in which molten aluminum is injected into a die defined about a laminated ferromagnetic core to form integral conductor bars and end rings.
Other materials, such as copper, are generally not conducive to die casting due to temperature limitations of the ferromagnetic core. Thus, the usual practice in the manufacture of copper bar induction rotors is to attach slotted copper end rings to each end of the rotor core, and individually attach the end turn portions of each conductor bar to the respective end ring by silver brazing or welding. The welding techniques (electron beam, TIG, MIG, etc.) tend to be expensive and difficult to control in high volume production. The brazing technique tends to be labor intensive and results in a higher resistance connection between the conductor bars and the end rings. Furthermore, the end rings themselves have to be precision machined and therefore add expense to the rotor manufacture.